CHARACTER AND RATE OF GROWTH IN STEMS 219 



plants as Corn, Beans, and Pumpkins grow slowly, White Mus- 

 tard and other plants with a low optimum grow rapidly. In gen- 

 eral, arctic plants have a lower optimum than tropical plants, and 

 consequently plants transferred from one region to the other 



FIG. 199. Pines grown much crowded and consequently producing slender 

 trunks. From Bulletin 24, North Carolina Geological and Economic Survey. 



usually do not thrive until they become acclimated, that is, 

 until the plant's protoplasm becomes adjusted to the tempera- 

 ture of the region. 



GROWTH TEMPERATURES IN FAHRENHEIT 



